JP7403170B2 - Locking nuts and how to tighten them - Google Patents

Description

The present invention relates to a double locking nut (hereinafter also referred to as a locking nut) that can prevent loosening after being tightened onto a bolt with a simple structure, and a method for tightening the same.

When fastening members using a bolt and a nut screwed into the bolt, a small amount of play (clearance) is provided between the threads of the bolt and the nut so that the nut rotates smoothly. Even if the nut is tightened with a large torque, the frictional force that acts between the member to be fastened and the head of the bolt, and between the nut and the member to be fastened is limited. For this reason, especially in machines with large vibrations such as construction machines, machine tools, and vehicles, a problem arises in that nuts tightened on bolts loosen due to vibration. As one of the means to solve such problems, locking double nuts are often used.

The above-mentioned locking nut is used to prevent two nuts from loosening by tightening two nuts onto a bolt and using the frictional force generated between the two nuts, and various proposals have been made in this regard. .

For example, Patent Document 1 discloses that after one thin nut and the thick nut that are connected to each other on their tapered surfaces are tightened together on a bolt, the thinner nut is further tightened within half a turn. A locking nut (combination nut) has been proposed.

Furthermore, Patent Document 2 discloses a convex first nut with a right-hand female thread and a small-pitch left-hand male thread that are screwed into a bolt, and a right-hand female thread and a left-hand female thread on the upper and lower parts of the inner periphery. A locking nut has been proposed, which comprises a second nut having a concave shape and a spiral inclined surface in a right-handed thread direction on the inner surface of the flange portion of the first nut and the lower end surface of the second nut. There is.

Furthermore, Patent Document 3 proposes a locking nut in which a notch having a constant taper angle is formed between a first nut part and a second nut part, and a continuous part is formed by this notch. There is. According to this locking nut, when the second nut part is forcibly rotated with respect to the first nut part in the direction shown, the continuous part is sheared, and the notch of the first nut part and the second nut part are opposed to each other. Since the surfaces are pressed together and the first nut part and the second nut part are pressed against the bolt on the axial center side of the bolt, loosening of the first nut part and the second nut part is prevented. .

Japanese Unexamined Patent Publication No. 53-110765 Special Publication No. 62-049489 Patent No. 3574698

However, in the locking nut proposed in Patent Document 1, in order to tighten the thin upper nut within half a turn, it is necessary to deform the thread of the bolt or deform the upper nut, which is unrealistic. There is a problem that. Furthermore, as shown in Fig. 17(b), even if a force is applied in the bolt axial direction, the force in the direction toward the bolt axis is balanced, so even if an additional half turn is applied, a pressing force in the bolt axial direction is generated and the bolt Although the frictional force for contact between the screw thread and the nut thread increases, the effect of pressing against the bolt axis side (caulking force) is small.

In addition, the locking nut proposed in Patent Document 2 has a convex portion and a concave portion that are screwed together or engaged with each other, so the structure of each nut is complicated and the manufacturing cost is high. be. Further, in Patent Document 2, the bolt is tightened in the axial direction of the bolt to prevent loosening, but as in the case of Patent Document 1, the effect of pressing against the bolt axis side is small.

Furthermore, in the locking nut proposed in Patent Document 3, after the connecting part is sheared by tightening the first nut part and the second nut part, which are integrated via the connecting part, to a bolt, the second nut part is sheared. By rotating the first nut part (upper nut) by a predetermined angle with respect to the first nut part (lower nut), the first nut part and the second nut part are pressed together in the axial direction of the bolt. As in the case, the effect of pressing against the bolt axis side is small, and there is a problem in that it is not always possible to reliably prevent both nuts from loosening.

The present invention was made in view of the above-mentioned problems of conventional locking nuts.The purpose of the present invention is to integrate the upper nut and the lower nut in a state where the upper nut and the lower nut are in full contact with each other on the tapered surface. After tightening the bolt, accurately position the upper nut by half a turn (180°) in the opposite direction (loosening direction) to reliably prevent both nuts from loosening, and the simple structure keeps manufacturing costs low. An object of the present invention is to provide a locking nut and a method for tightening the same.

A locking nut according to the present invention for achieving the above object is composed of two nuts, an upper nut and a lower nut, which are screwed onto a bolt, and the connecting surface of these two nuts is a plane perpendicular to the axis of the bolt. A locking nut having a tapered surface inclined at a predetermined angle relative to the top nut, the upper nut and the lower nut having an engaging protrusion protruding from one location near the outer periphery of one of the tapered surfaces, and an engaging protrusion protruding from the outer periphery of one of the tapered surfaces, An engagement recess formed at two radially opposite locations near the outer periphery of the tapered surface, and an engagement recess engaged with the engagement protrusion formed by the engagement protrusion and the engagement recess. The present invention is characterized by comprising a guide portion that allows and restricts the nut to rotate half a turn toward the loosening side.

Further, in the method for tightening a locking nut according to the present invention, the upper nut and the lower nut are joined so that the engagement protrusion engages with one of the engagement recesses, and the tapered surfaces of the nuts are joined in parallel to each other. After tightening the bolt as one unit, turn the upper nut half a turn in the loosening direction to engage the engagement protrusion with the other engagement recess, and then loosen the upper nut after tightening with respect to the lower nut. It is characterized by positioning at a position rotated half a turn in the direction.

According to the present invention, the upper nut and the lower nut are integrally attached to the bolt with the engagement protrusion of the lower nut engaged with one of the engagement recesses of the upper nut, and with their tapered surfaces joined in parallel. When the upper nut is turned half a turn in the loosening direction after being tightened, the engagement protrusion engages the other engagement recess to accurately position the upper nut in the circumferential direction relative to the lower nut. The convex portions of the tapered surface of the nut overlap and press each other, and a high pressing force (force perpendicular to the tapered surface) is always applied to the pressing portion. Since the horizontal component of this pressing force presses both nuts in the direction of the shaft center, there is no play between the female threads of both nuts and the male thread of the bolt, and as a result, loosening of both nuts is reliably prevented. It will be done.

In addition, the two nuts constituting the locking nut according to the present invention can be easily cut at the same time by cutting one nut member diagonally at the middle part in the height direction. Since it can be manufactured in a number of steps, manufacturing costs can be kept low.

FIG. 2 is a front view showing a state in which the locking nut according to Embodiment 1 of the present invention is screwed onto a bolt. FIG. 1 is a front view of the locking nut according to Embodiment 1 of the present invention. FIG. 3 is a view in the direction of arrow AA in FIG. 2 (bottom view of the upper nut). A view in the direction of arrow BB in FIG. 2 (plan view of the lower nut). (a) to (c) are cutaway front views showing a method for tightening a locking nut according to Embodiment 1 of the present invention in the order of steps; (a) is a sectional view taken along line DD in FIG. 5(a), (b) is a sectional view taken along line EE in FIG. 5(b), and (c) is a sectional view taken along line FF in FIG. 5(c). . (a) shows the locking nut according to Embodiment 1 of the present invention, when the upper nut is turned half a turn after tightening the nut with a 1/2 pitch gap between the tapered surfaces of both nuts. A schematic diagram illustrating the state of the tapered surfaces of both nuts, (b) is the same locking nut as in FIG. 7(a), but without a 1/2 pitch gap between the tapered surfaces of both nuts. Here is a schematic diagram illustrating the state of the tapered surface where the upper nut cannot be rotated half a turn even if the upper nut is attempted to be rotated half a turn after tightening. FIG. 3 is a front view showing another form of the locking nut according to Embodiment 1 of the present invention. FIG. 7 is a cutaway front view showing a state in which a locking nut according to Embodiment 2 of the present invention is fastened to two plate members with a bolt. FIG. 6 is a front view of a locking nut according to a second embodiment of the present invention. FIG. 11 is a view in the direction of arrow GG in FIG. 10 (bottom view of the upper nut). FIG. 11 is a view in the direction of arrow HH in FIG. 10 (plan view of the lower nut). FIG. 7 is a front view of a locking nut according to Embodiment 3 of the present invention. FIG. 14 is a plan view of the locking nut of FIG. 13; FIG. 14 is a front view of the locking nut shown in FIG. 13 in a functioning state; FIG. 3 is a schematic front view for explaining the dimensions of each part of the upper nut of the locking nut and the force that acts on the upper nut from the lower nut when the upper nut is rotated half a turn in the opposite direction. (a) (b) Schematic diagram for explaining the force acting on one thread of the screwing surface (contact surface) shown in FIG. 17(a) of the upper nut and bolt in FIG. 16 using FIG. 17(b) Enlarged view. FIG. 7 is a schematic front view for explaining deformation of an upper nut having the same form as the upper nut of Embodiment 3 during a half turn.

Embodiments 1 to 3 of the present invention will be described below in order based on the accompanying drawings.

<Embodiment 1>
FIG. 1 is a side front view showing a state in which a locking nut according to Embodiment 1 of the present invention is screwed onto a bolt, and FIG. 2 is a front view of the locking nut according to Embodiment 1 of the present invention. 3 is a view in the direction of arrow AA in FIG. 2 (a bottom view of the upper nut), and FIG. 4 is a view in the direction of arrow BB in FIG. 2 (a plan view of the lower nut).

As shown in FIG. 1, the locking nut 1 according to the first embodiment is composed of two nuts 2 and 3 that are screwed onto a bolt 10. Hereinafter, the upper nut 2 in FIG. 1 will be referred to as the "upper nut 2", and the lower nut 3 will be referred to as the "lower nut 3".

The upper nut 2 and the lower nut 3 are hexagonal nuts, as shown in FIGS. 3 and 4, and the pitch P (FIG. Female threads 2a and 3a are formed with the same pitch P as in the case (see).

In addition, as shown in FIGS. 1 and 2, the joint surface of the upper nut 2 and the lower nut 3, that is, the bottom surface of the upper nut 2 and the upper surface of the lower nut 3, is a surface perpendicular to the axis CL of the bolt (see FIG. The tapered surfaces 2A and 3A are inclined at a predetermined angle θ with respect to the horizontal plane in FIG. Here, as shown in FIG. 2, in each of the tapered surfaces 2A and 3A of the upper nut 2 and lower nut 3, the thicker side portions are convex portions 2A1 and 3A1, and the thinner side portions are convex portions 2A2. , 3A2.

By the way, as shown in FIGS. 2 to 4, if the horizontal component of the length of each tapered surface 2A, 3A of the upper nut 2 and lower nut 3 is L, the inclination angle θ of each tapered surface 2A, 3A will be described later. For this reason, it is set to the value expressed by the following equation (1).
θ≧tan-1(P/2L)…(1)

In the first embodiment, as shown in FIGS. 2 and 4, a short column-shaped positioning pin 4 as an engagement protrusion is provided at one location in the circumferential direction of the convex portion 3A1 of the tapered surface 3A of the lower nut 3. It is installed vertically. Here, the height h (see FIG. 2) of the positioning pin 4 is set to approximately the same height as 1/2 (0.5P) of the pitch P (see FIG. 1) of the male thread 10a of the bolt 10. . That is, the height h of the positioning pin 4 has a relationship expressed by the following equation (2) with respect to the pitch P of the male thread 10a of the bolt 10.
h≒P/2…(2)

Further, as shown in FIG. 3, two locations on the same circumference facing each other on the diameter of the tapered surface 2A of the upper nut 2 (two locations separated by an angle of 180° in the circumferential direction, that is, the convex portion 2A1 of the tapered surface 2A) In the recess 2A2), two circular engagement holes 51 and 52 are provided as an example of an engagement recess in which the cylindrical positioning pin 4 provided upright on the lower nut 3 selectively engages. These two engagement holes 51 and 52 are located at both ends of the guide 6, which includes a semicircular groove that functions as a guide and is formed in the tapered surface 2A. Here, when the guide 6 is a groove, the groove is formed in a semicircular shape centered on the axis of the upper nut 2, and its width w is approximately equal to the inner diameter φd of the engagement holes 51 and 52. (w=φd), and the depth s is set to a value substantially equal to the height h of the pin 4 (s=h). Note that the inner diameter φd of the engagement holes 51 and 52 is set slightly larger than the outer diameter φD of the positioning pin (φd>φD).

The above-described positioning pin 4, the two engagement holes 51 and 52 that the positioning pin 4 selectively engages with, and the guide that slides and guides the positioning pin 4 between the two engagement holes 51 and 52. Reference numeral 6 constitutes an example of a positioning structure for accurately positioning the upper nut 2 by half a turn in the loosening direction with respect to the lower nut 3. Although the guide 6 is shown as a groove in FIGS. 2 and 3, it has a tapered bottom so that the tapered surface 2A of the upper nut 2 can overcome the positioning pin 4 when the upper nut 2 begins to be rotated half a turn in the loosening direction. There are also shallow grooves.

Next, a method for tightening the locking nut 1 of the first embodiment configured as described above will be described below based on FIGS. 5 and 6.
5(a) to 5(c) are cutaway front views showing the method of fastening two plates using the locking nut and bolt according to the first embodiment in the order of steps, and FIGS. 6(a) to 5(c) ) is a sectional view taken along lines DD, E-E, and FF in Figures 5(a) to (c), and Figure 7(a) is a cross-sectional view of the upper nut 2 and lower nut 3 after they have been tightened together. FIG. 2 is a diagram schematically showing the state of each tapered surface when No. 2 is rotated half a turn in the loosening direction.

As shown in FIG. 5, when two plates 11 and 12 are fastened using the locking nut 1 and bolt 10 according to the first embodiment, they are stacked one on top of the other, as shown in FIG. 5(a). A bolt 10 is passed from below through circular bolt holes 11a and 12a formed in the two plates 11 and 12, respectively, and the head 10A of the bolt 10 is abutted against the bottom surface of the lower plate 12. Then, the tapered surfaces 2A and 3A are brought into surface contact with the part of the bolt 10 that protrudes upward from the plate material 11 on the upper side of the threaded part 10B, so that the locking nut looks like the upper nut 2 and the lower nut 3 are integrated. 1 using a socket wrench. Specifically, the tapered surfaces 2A and 3A of the upper nut 2 and lower nut of the locking nut 1 are joined to each other, and the positioning pin 4 installed vertically on the lower nut 3 is connected to the upper nut 2 and the lower nut 3 as shown in FIG. 6(a). While engaging one of the engagement holes 5 formed in the tapered surface 2A of the upper nut 2, tighten both nuts 2 and 3 using a tool such as a socket wrench (not shown) in the tightening direction (Fig. 5(a) ) in the direction of the arrow, opposite to the direction of tightening.
Then, the upper nut 2 and the lower nut 3 move downward as a unit along the threaded portion 10B of the bolt 10, and as shown in FIG. comes into contact with. From this state, both nuts 2 and 3 are tightened to bolt 10 with a predetermined torque.

Thereafter, the upper nut 2 is rotated by half a turn (rotated by 180°) in the loosening direction (in the direction of the arrow shown in FIG. 5(b)). This half-turn in the loosening direction of the upper nut 2 is caused by the positioning pin 4 erected on the tapered surface 3A of the lower nut 3 formed on the tapered surface 2A of the upper nut 2, as shown in FIG. 6(b). A semicircular groove-shaped guide 6 is slidably guided. That is, during the half-rotation process of the upper nut 2 in the loosening direction, the guide 6 formed on the tapered surface 2A of the upper nut 2 is guided by the positioning pin 4 as shown in FIG. 6(c). It will move by half a rotation from the position (a).

When the upper nut 2 rotates half a turn in the loosening direction, the other engagement hole 52 formed in the tapered surface 2A of the upper nut 2 is inserted into the positioning pin 4 provided upright on the lower nut 3, as shown in FIG. 6(c). is engaged, further rotation of the upper nut 2 in the loosening direction is prevented, and the upper nut 2 is accurately positioned relative to the lower nut 3 in the circumferential direction. Further, when the upper nut 2 rotates half a turn in the loosening direction, the recess 2A2 of the tapered surface 2A of the upper nut 2 moves away from the convex portion 3A1 of the tapered surface 3A of the lower nut 3 (upward) of the male thread 10a of the bolt 10. Move by 1/2 of pitch P (=P/2). Then, as shown in FIG. 5(c), the convex portion 2A1 of the tapered surface 2A of the upper nut 2 overlaps the convex portion 3A1 of the tapered surface 3A of the lower nut 3, and the concave portions of the tapered surfaces 2A and 3A of both nuts 2 and 3 overlap. A predetermined gap δ is formed between 2A2 and 3A2.

Next, the inclination angle θ of the tapered surfaces 2A and 3A for obtaining the loosening effect by rotating the upper nut 2 by half a turn in the loosening direction described above will be explained with reference to FIG. 7(a).
After tightening the upper and lower nuts 2 and 3 to a predetermined torque, when the upper nut 2 is turned half a turn in the loosening direction, the point a of the convex portion 2A1 on the tapered surface 2A of the upper nut 2 before the half turn moves upward by P/2. At the same time, it rotates half a turn and moves to point a' in FIG. 7, and point b of the concave portion 2A2 of the tapered surface 2A of the upper nut 2 moves to point b' in FIG. δ is formed.
Therefore, the upper nut 2 rotates half a turn in the loosening direction, and as shown in FIG. When point a of surface 2A and point b of convex portion 3A1 of tapered surface 3A of lower nut 3 are in contact (point contact), the inclination angle of each tapered surface 2A, 3A of upper nut 2 and lower nut 3 is θ is expressed by the following equation (3).
θ=tan-1(P/2L)...(3)

However, in reality, even if you tighten the upper nut 2 and lower nut 3 together with the desired torque and then try to loosen the upper nut 2 by half a turn, the point a of the convex portion 2A1 of the tapered surface 2A of the upper nut 2 cannot reach point b of the convex portion 3A1 of the tapered surface 3A of the lower nut 3. The reason is as follows. That is, as shown by the solid line in FIG. 7(b), when the tapered surfaces 2A and 3A of both nuts 2 and 3 are joined, point a of the upper nut 2 is closer to the inner diameter edge x of the screw 2a of the upper nut 2. It is located at the bottom. Therefore, even if you turn the upper nut 2 after tightening by half a turn toward the loosening side and try to raise the inner diameter edge x of the screw by half a pitch so that it is in the direction 2' shown by the two-dot chain line, it will not work. A hits the protrusion 3A1 of the lower nut 3 in front of point b before making a half turn, and the upper nut 2 cannot be rotated any further.
In order for point a to reach point b by half a rotation of the upper nut 2, the tapered surface 2A of the upper nut 2 must be deformed, or when the upper and lower nuts 2 and 3 are tightened, the taper surfaces of both nuts 2 and 3 must be deformed. It is necessary to maintain a gap of 1/2 the screw pitch between 2A and 3A. Therefore, FIG. 7A shows an example in which a gap corresponding to 1/2 of the thread pitch is provided in advance between the tapered surfaces 2A and 3A of the upper nut 2 and the lower nut 3.
In addition, in FIG. 7(a), when the upper nut 2 is rotated half a turn in the loosening direction, in order to bring the points a and b into surface contact, θ in the above equation (3) must be increased or It is conceivable to reduce the gap between the tapered surfaces of the upper nut 2 and lower nut 3 to 1/2 or less of the screw pitch before starting rotation.

The above equation (3) indicates the inclination angle θ of each tapered surface 2A, 3A when the convex portions 2A1, 3A1 of each tapered surface 2A, 3A of the upper nut 2 and lower nut 3 are in point contact with each other. If the angle θ is larger than the value expressed by equation (3), that is,
θ>tan ^-1 (P/2L)...(4)
When set to the value shown by , the convex portions 2A1 and 3A1 of the tapered surfaces 2A and 3A of the upper nut 2 and lower nut 3 come into surface contact with each other. In this way, when the convex portions 2A1 and 3A1 of the tapered surfaces of the upper nut 2 and the lower nut 3 are in surface contact with each other, the thickness of the upper nut 2 is made thinner than the thickness of the lower nut 3 as shown in FIG. Alternatively, by making the material of the upper nut 2 smaller in hardness than the material of the lower nut 3, the upper nut 2 that has been rotated half a turn will be more likely to be elastically deformed with respect to the lower nut 3. Reliable surface contact between the convex portions 2A1 and 3A1 of the tapered surfaces 2A and 3A of the lower nut 3 can be realized.

As described above, in the locking nut 1 according to Embodiment 1, the upper nut 2 and the lower nut 3 are arranged such that the positioning pin 4 erected on the lower nut 3 is formed on the tapered surface 2A of the upper nut 2. After engaging the upper nut 2 and the bolt 10 with the taper surfaces 2A and 3A of both nuts 2 and 3 connected to each other, the upper nut 2 is turned half a turn in the loosening direction. By causing the positioning pin 4 to engage with the other engagement hole 52, the upper nut 2 can be accurately positioned relative to the lower nut 3 in the circumferential direction. As a result, a high pressing force (force perpendicular to the tapered surfaces 2A, 3A) is always applied to the pressing portion where the convex portions 2A1, 3A1 of the tapered surfaces 2A, 3A of both nuts 2, 3 overlap and press each other.

Here, the pressing force that acts on the contact portions when the convex portions 2A1, 3A1 of the tapered surfaces 2A, 3A of the upper nut 2 and lower nut 3 contact each other will be explained with reference to FIGS. 16 and 17. do.

For convenience of explanation of the loosening action of the upper nut 2, FIG. This is a diagram schematically showing the state in which it is normally in the form of a nut.
In FIG. 16, L: thickness of upper nut 2, D: outer diameter of upper nut 2, d: inner diameter of upper nut 2, P: upward pressing force of lower nut 3 (not shown) acting on upper nut 2. (generated by the contact between the tapered surface 2A of the upper nut 2 and the tapered surface 3A of the lower nut 3), R: reaction force received by the upper nut 2 from the bolt 10 (generated by the pressing force P acting on the upper nut 2); do.

Now, as shown by the dotted line in FIG. 16, the moment around the contact point A between the female thread 2a of the upper nut 2 tilted by the upward pressing force P on the tapered surface of the lower nut and the male thread 10a of the bolt 10 is P× Since 1/2(D+d)=RL, the reaction force R is expressed as R=P×(D+d)×1/2L.
From the above formula, it is possible to increase the reaction force R by (a) increasing P, (b) increasing D(d), and (c) decreasing L. Although not expressed in the above formula for the reaction force R, it is also possible to directly increase the reaction force R by deforming the upper nut 2.

On the other hand, as an alternative to increasing the outer diameter D of the upper nut 2, it is considered effective to attach a deformable flange to the nut 2 without increasing the outer diameter of the upper nut 2 itself. It is also considered effective to reduce the thickness L of the upper nut in order to deform the upper nut.

Next, FIGS. 17(a) and 17(b) show that conventional locking nuts such as those disclosed in Patent Documents 1 to 3, in which the contact surfaces of the upper nut and the lower nut are tapered to prevent loosening, have a sufficient locking effect. We will discuss the reasons why it was not obtained.
17(a) and 17(b) consider the effect of an upward pressing force P at the contact point between the upper nut 2 of a conventional locking nut and the screw of the bolt 10 on the contact surface of one male thread and one female thread. It is a schematic diagram. FIG. 17(b) is a schematic enlarged view of one thread of the bolt 10 and nut 2 in FIG. 17(a).

In FIG. 17(b), when the above pressing force P=Σp, the force ph parallel to the threads is almost balanced between the left and right threads 10a and 2a of the bolt 10 and nut 2. Therefore, even if a pressing force P acts in the vertical direction, if the force ph parallel to the threads is balanced by the contact surfaces of the left and right threads, there will be no change in the relative position of the contact surfaces of the threads, so there will be no change in the relative position of the contact surfaces of the threads. It is not possible to obtain strong caulking force. In FIG. 17(b), p is a pressing force that acts on one screw thread, and pn is a component force that acts on the contact surface of one screw thread in the orthogonal direction.

The upper nut 2 and lower nut 3 constituting the locking nut 1 according to the first embodiment described above can be easily assembled by cutting one nut diagonally (at the angle of the tapered surfaces 2A and 3A) at the middle part in the height direction. Since the locking nut 1 of the present invention can be manufactured easily, the structure can be simplified and the manufacturing cost can be kept low.

<Embodiment 2>
Next, a second embodiment of the present invention will be described below based on FIGS. 9 to 12.

FIG. 9 is a cutaway front view showing a locking nut according to Embodiment 2 in which two plates are fastened together with a bolt, and FIG. 10 is a front view of the locking nut according to Embodiment 2. 11 is a view taken along the line GG in FIG. 10 (bottom view of the upper nut), and FIG. 12 is a view taken along the line HH in FIG. 10 (plan view of the lower nut). The same elements as shown in FIGS. 1 to 8 are denoted by the same reference numerals, and their explanation will not be repeated hereafter.

A locking nut 1A according to the second embodiment is composed of an upper nut 2 and a lower nut 3 with flanges (flanges) 2F and 3F. The lower surface of the circular flange 2F integrally formed on the lower end surface of the upper nut 2 is a flat taper inclined at an angle θ shown in the figure with respect to a plane (horizontal plane) perpendicular to the vertical axis CL of the bolt 10. The upper surface of the circular flange 3F, which constitutes the surface 2A and is integrally formed on the upper end of the lower nut 3, is inclined by the angle θ shown in the figure with respect to a plane (horizontal plane) orthogonal to the vertical axis CL of the bolt 10. It constitutes a flat tapered surface 3A. Here, the inclination angle θ of each tapered surface 2A, 3A of the upper nut 2 and lower nut 3 is set to a value expressed by the above equation (1).

Also, in the locking nut 1A according to the second embodiment, similarly to the locking nut 1 according to the first embodiment, the convex portion 3A1 side of the tapered surface 3A, which is the upper surface of the flange 3F of the lower nut 3, is At one location in the circumferential direction, a short column-shaped positioning pin 4 serving as an engagement protrusion is vertically provided (see FIGS. 10 and 12).

In addition, as shown in FIG. , engagement notches 51 and 52, which are examples of engagement recesses, are respectively formed to selectively engage with the positioning pin 4 provided upright on the lower nut 3. These two engagement notches 51 and 52 are present at both ends of the guide 6, which includes semicircular grooves formed in the tapered surface 2A. Here, the positioning pin 4 is guided by sliding between the two engagement notches 51 and 52 that selectively engage the positioning pin 4, and the two engagement notches 51 and 52. The guide 6 forms a positioning structure for accurately positioning the upper nut 2 with respect to the lower nut 3 in the circumferential direction. In FIGS. 9 to 11, 7 is a counterbore formed on the tapered surface 2A of the upper nut 2 on the inside of the guide 6 in the radial direction. The counterbore portion 7 is provided to facilitate deformation of the two tapered surfaces 2A and 3A, and its depth and size vary depending on the thickness, diameter, and material of the flange.

Therefore, in the locking nut 1A according to the second embodiment described with reference to FIGS. 9 to 12, the upper nut 2 is similar to the locking nut 1 according to the first embodiment described above. The positioning pin 4 provided upright on the lower nut 3 engages one of the engagement notches 51 formed in the tapered surface 2A of the upper nut 2, and each taper of both nuts 2 and 3 After tightening the bolt 10 as one unit with the surfaces 2A and 3A joined together, the upper nut 2 is turned half a turn in the loosening direction.
Here, in order to tighten the upper and lower nuts 2 and 3 as one body to the bolt 10, the tapered surfaces 2A and 3A of both nuts 2 and 3 are joined, and the upper Tighten nut 2 with a socket. Note that ratchet teeth with a serrated cross section are formed on the outer circumferential side of the counterbore 7 on the lower surface of the upper nut 2 to ensure that both nuts 2 and 3 rotate together when the upper nut 2 is tightened by the socket. It may be supplemented.

When the upper nut 2 is turned half a turn in the loosening direction, the upper nut 2 is turned half a turn until the positioning pin 4 is engaged with the other engagement notch 52. Since the part where the flange 2F is thinner than the upper nut 2 is the flange part 2F, when the upper nut 2 is turned half a turn and the convex parts 2A1 and 3a1 of the tapered surfaces 2A and 3A of both nuts 2 and 3 come into contact with each other, The flange portion 2F is slightly warped upward and can be easily rotated by half a rotation. Therefore, the convex portion 2A1 of the tapered surface 2A of the upper nut 2 can be easily positioned by half a rotation relative to the convex portion 3A1 of the tapered surface 3A of the lower nut 3 in the circumferential direction. As a result, as in the first embodiment, there is play between the female threads 2a and 3a of the upper nut 2 and the lower nut 3 (see FIGS. 11 and 12) and the male thread 10a of the bolt 10 (see FIG. 9). (Clearance) is eliminated, and the flange 2F is deformed, thereby achieving the effect that loosening of both nuts 2 and 3 can be reliably prevented.

Further, the upper nut 2 and the lower nut 3, which form the tapered surfaces 2A and 3A with the flanges 2F and 3F, which constitute the locking nut 1A according to the second embodiment, have a simple structure and can be easily and easily installed. Since the locking nut 1A is manufactured, the manufacturing cost of the locking nut 1A can be kept low.

In the first and second embodiments described above, the positioning pin 4 is provided upright on the tapered surface 3A of the lower nut 3, and two engagement holes (or engagement notches) 51 are provided on the tapered surface 2A of the upper nut 2. , 52 and a groove, but on the contrary, a positioning pin is provided protruding from the tapered surface 2A of the upper nut 2, and two engagement holes (or engagement holes) are provided on the tapered surface 3A of the lower nut 3. A guide including a matching notch) and a groove may be formed. Here, the engagement hole and the engagement notch can be arbitrarily selected.

<Embodiment 3>
Next, a third embodiment of the present invention will be described below based on FIGS. 13 to 15.

The locking nut 1B of the third embodiment is a modification or application of the second embodiment, and has the following unique configuration compared to the second embodiment. This will be explained below.

First, the lower nut 3 is the same as the lower nut 3 of the first embodiment because the tapered surface 3A is formed on the upper surface of the lower nut itself and does not include the flange 3F. Next, the upper nut 2 has an outer diameter smaller than the outer diameter of the lower nut 3, for example, about 1/2 of the outer diameter of the lower nut 3. The upper nut 2 has a lower tapered surface 2A formed into a hexagonal flange 21F having the same outer diameter and outer shape as the lower nut 3 in a plan view. Further, the tapered surface 2A of the upper nut 2 is provided with a counterbore portion 7 for the same purpose as in the second embodiment.

The lower nut 3 is equipped with a positioning pin 4 at one location on the outer circumference, while the lower surface of the flange 21F forming the tapered surface 2A of the upper nut 2 has a position corresponding to the pin 4 and a position 180 mm on the flange diameter from that position. Locking notches 51 and 52 (or notches) into which the pin 4 is fitted are provided at two positions separated by a degree. Note that the locking notch may be a locking hole.

In the locking nut 1B of the third embodiment, the tapered surfaces 2A and 3A of the upper nut 2 and lower nut 3 are made parallel, and the positioning pin 4 is joined with the first engagement notch 51, The two nuts 2 and 3 are set together in a socket wrench and screwed onto the bolt 10. This point is the same as in the case of the locking nut 1 of the first embodiment described above.

When the upper nut 2 and lower nut 3 are integrally fastened to the bolt 10 with a predetermined torque, the upper nut 2 is rotated half a turn toward the loosening side, and the positioning pin 4 is inserted into the second engagement notch of the flange 21F of the upper nut 2. 52 and position it. Then, the portion provided with the second engagement notch 52 located on the outer flange 21F of the upper nut 2 is deformed by the upward force of the convex portion 3A1 of the tapered surface 3A of the lower nut 3, and the upper To eliminate play between the female thread of a nut 2 and the male thread of a bolt 10. This prevents the upper nut 2 and lower nut 3 from loosening from the bolt 10.

The upper nut 2 of the third embodiment described above is designed for the purpose of increasing the outer diameter D of the upper nut 2 discussed in the explanation of the first embodiment (paragraphs 0033 and 0034) and deforming the upper nut 2. As schematically illustrated in FIG. 18 when the upper nut 2 is viewed from the front, the nut itself is thin in wall thickness and vertical thickness, and a hexagonal washer part (with the same diameter as the lower nut 3) is formed. Flange) 2F is provided.
After fastening the upper nut 2 and lower nut 3 formed in this way to the bolt 10 together with a socket wrench, when the upper nut 2 is rotated 180 degrees in the opposite direction to the tightening direction along the axis of the bolt 10, as shown in FIG. Since the washer portion 21F in FIGS. 13 to 15 (the washer portion 2F in FIG. 18) is deformed, the contact area between the bolt 10 and the thread of the bolt 10 of the upper nut 2 increases, and the The forces ph parallel to the left and right screw threads explained in b) also become uneven, resulting in a large "caulking force". Note that it is also effective to form the upper nut 2 from a softer material in order to easily deform the upper nut 2. In the upper nut 2 of FIGS. 13 to 15 and 18, even if the thickness of the upper nut 2 in the vertical direction is reduced, the washer portions 21F and 2F are provided, so the outer diameter D of the upper nut 2 is substantially increased. As a result, the reaction force R also increases.

In the first to third embodiments described above, the locking nut 1 consists of two normal hexagonal nuts, an upper nut 2 and a lower nut 3, and two flanged nuts, an upper nut 2 and a lower nut 3. The present invention has been applied to a locking nut 1A consisting of a locking nut 1A, a locking nut 1B comprising an upper nut 2 with a flange, and a lower nut 3 of the same type as the flange of the upper nut 2. It is similarly applicable to any other type of locking nut consisting of two nuts.

In addition, the application of the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the technical ideas described in the claims, specification, and drawings. Of course.

1, 1A, 1B Locking nut of the present invention 2 Upper nut 2A Tapered surface on the lower surface of the upper nut 2F, 21F Flange of the upper nut (flange part)
3 Lower nut 3A Tapered surface on the upper surface of the lower nut 3F Flange of the lower nut 4 Positioning pin (engaging protrusion)
51, 52 Engagement hole, engagement notch (engagement recess)
6 Guide including groove (guide part)
7 Counterbore 10 Bolt CL Bolt axis P Bolt thread pitch θ Incline angle of nut taper surface

Claims (9)

A locking nut consisting of two nuts, an upper nut and a lower nut, which are screwed onto a bolt, and the joining surface of these two nuts is a tapered surface inclined at a predetermined angle with respect to the plane perpendicular to the axis of the bolt. There it is,
The upper nut and lower nut are
an engagement protrusion protruding from one location near the outer periphery of one of the tapered surfaces;
engaging recesses formed at two locations near the outer periphery of the other tapered surface facing each other in the diametrical direction;
a guide portion formed by the engagement protrusion and the engagement recess that allows and restricts the engagement recess engaged with the engagement protrusion from rotating half a turn toward the loosening side of the upper nut;
Locking nut with. The engagement protrusion is composed of a short column-shaped positioning pin,
The engagement recess is configured with two engagement holes or engagement notches into which the pin fits,
The locking nut according to claim 1, wherein the guide portion is configured with a pin passage including a semicircular groove for guiding the pin formed between the two engaging recesses. The upper nut and the lower nut are each provided with a flange portion forming the tapered surface, the engaging protrusion is provided protruding near the outer periphery of one flange portion, and the engaging protrusion is provided at the two locations near the outer periphery of the other flange portion. The locking nut according to claim 1 or 2, wherein an engaging recess and the guide portion are formed. The upper nut has a smaller diameter than the lower nut, and has a hexagonal flange approximately the same shape as the lower nut on its lower tapered surface, and the lower nut has an upper tapered surface with the same external shape as the hexagonal flange. The engagement protrusion protrudes near the outer periphery of the tapered surface of the lower nut, and the engagement recess and the guide are provided at two diametrical locations near the outer periphery of the hexagonal flange portion of the upper nut. The locking nut according to claim 1 or 2, wherein the locking nut has a portion formed therein. The locking nut according to any one of claims 1 to 4, wherein the thickness of the upper nut is set to be thinner than the thickness of the lower nut. The locking nut according to any one of claims 1 to 5, wherein the hardness of the upper nut is set lower than the hardness of the lower nut. The locking nut according to any one of claims 1 to 6, wherein the angle of inclination of the tapered surfaces of the upper nut and the lower nut is approximately the same angle as the pitch angle of the thread of the bolt. The locking nut according to any one of claims 1 to 6, wherein a counterbore is formed on the tapered surface of the upper nut, leaving an outer peripheral edge. A method for tightening a locking nut according to any one of claims 1 to 8, comprising:
After tightening the upper nut and the lower nut as one body with the bolt in a state where the engaging protrusion engages with one of the engaging recesses and their tapered surfaces are joined in parallel, the upper nut is loosened. The upper nut, after being tightened, is positioned at a position where the upper nut is rotated half a turn in the loosening direction with respect to the lower nut. How to tighten locking nuts.

Images